Accurate early diagnosis is of paramount importance in the treatment of disease. For many diseases, however, diagnostic systems have not been developed or are economically impractical. In this application, a new, proprietary immunodiagnostic system, based on gene-fusion technology, will be refined. This system biologically couples disease specific immunodominant gene products to a reporter enzyme and uses the resulting hybrids (epitope-enzyme conjugates) as diagnostic reagents. The technology to be developed can be extended to virtually any human or animal pathogens and most autoimmune disorders at a fraction of the cost normally associated with these endeavors. The specific aims of this proposal are to purify previously constructed HIV-1-gp120 epitope-enzyme conjugates and assess the improvements in sensitivity and specificity afforded by the use of purified reagents. To achieve this aim, immunoaffinity columns capable of binding to all the hybrids produced by this method will be prepared. The second aim is to investigate the development of enzyme conjugates specific for other significant human diseases. Future goals will be to develop a full range of immunodiagnostic reagents for the diagnosis of medically important diseases.